A diet high in fiber from vegetables and fruit was shown to produce an increased immune response to allergens and to reduce the instance of allergic asthma in studies of mice by Benjamin Marsland from Lausanne University Hospital in Switzerland and colleagues that was published in the Jan. 6, 2014, issue of the journal Nature Medicine.
The researchers fed three groups of mice a normal diet, a low-fiber diet, and a high-fiber diet. The low-fiber diet was equivalent to the amount of fiber most people in Europe and the United States eat daily in vegetables and fruit.
The mice that ate the high-fiber diet had a high tolerance for dust mites compared to the other two groups of test mice.
The researchers found that the immunity to allergens and a resistance to the development of asthma was the result of a high-fiber diet.
A diet high in fruits and vegetables makes a larger amount of fermentable fiber available to bacteria in the gut. The bacteria convert the fiber into short-chain amino acids. The amino acids enter the blood stream through the intestines and end up in bone marrow. The bone marrow manufactures immune proteins to common allergens and produces anti-inflammatory proteins that help prevent asthma.
The researchers plan human studies to confirm the mouse trial results. Mice and human digestive and lung systems are almost identical.
The researchers stress that eating more fruit and vegetables can prevent allergies, allergic asthma, and asthma.